Obviously I don't have a crystal ball, so let's see in a couple of years... but atm I think PS4/XB1 were kind of an anomaly. I don't see a current generation of "Pro" consoles as likely to be released as previous gen, for different reasons.

1. The OG PS4 and Xbox One had a "relatively" weak hardware for the time, they were built with a lower price point in mind and to be profitable (almost) right from the start (Xbox One even had corners cut to bundle Kinect). This is not the case anymore with PS5/Series X as they both have a more expensive and future-proof design. This time offering a "pro upgrade" with sensible advantages for the end-user would require a greater effort and an higher price tag.

2.  There is not a tech opportunity window for mid-gen refreshes. PS4 Pro and One X came with the arrival of 4K and HDR displays, PS5 and Serie X added HDMI 2.1 capabilities support. I don't see any imminent tech upgrade for the living room that could justify console upgrades.

3. There is less incentive on both parts for an upgrade. MS was evidently lagging in 2016-2017, they needed an opportunity to catch-up with new hardware. Sony on the other hand was interested to maintain their tech leadership for 3rd party games, so they've released their own 4k hardware proposal in advance, rather than running the risk of having to cut the price (and profits) of their vanilla console.
This time MS is much better positioned with a very competent console, new 1st party studios and Gamepass. Looking at acquisitions from both sides it seems like the competition is shifting from tech leadership to exclusive content leadership. Sony is likely interested to give a stronger push to their VR proposition (as it would give them the opportunity to offer even more exclusive content). If they released a "pro" upgrade it would most likely cannibalize thier own PSVR2 sales. MS already supports both and hi-end and a low-end SKU, adding another platform to support on top of that would over complicate things.

4. As others have stated, hardware shortages will slow things even more and will give even more incentives to Sony/MS to build "slim" versions with smaller dies, rather "pro" versions with large dies.

As for the PS5 roadmap I'm expecting.

- A slim version earlier than usual but with the same price tag (made to cut down costs and improve availability).

- Further down the line a "bigger" launch for the PSVR2, maybe alongside with the first price-cut of the vanilla console and the release of an alternate SKU with a larger SSD.

 Surely the only thing that would stagnate would be console resolution and the 60fps target. 

I know, so true, I'll wait to 2034 before I play games.

I don't wanna play anything below 16k, full ray-traced at 240 fps.

I'm so happy to wait 13 years for those life's changing features.

Due to shortages and delays, I can actually see the PS6 not launching until 2028, so basically an eight year generation which would be 7 years if not for covid.

I do agree that we will see slim versions in a few years and I do think a pro might be unnecessary.

I hope this generation is not short.

Holiday 2022 - PS5 Slim
Holiday 2023 - Sony is working on PSVR2 and I expect a PS5 Pro to release along side of it. PS5 Pro to target 8k and flawless 4k 60 fps.

With the current chip shortage, I wouldn't be surprise to see a one year delay for PS5 Slim to 2023 and PS5 Pro to 2024.

So many people claim that the Xbox One and PS4 were too weak for their time. But it's just because of 2013 PCs, right? Because Xbox One and PS4 were very clear generational leaps in performance from their predecessors, just as generational leaps had been before then. 

Maybe it wouldn't seem so apparent if we got Xbox One and PS4 in 2011 or 2012 with the same specs they ended up with.

I'll also mention that I completely forgot PSVR 2. The only prediction I'll make is the vague window of 2023-2024. There's little chance PSVR 2 launches in 2022, since we still know so little.

Even assuming that PS4 Slim to PS4 Pro dropped off in favour of Slim model later down the gen, I still personally find it hard to believe that PS4 Pro didn't reach 10m lifetime sales. Just two facts that we have: PS4 sold around 60m consoles in the period from Slim/Pro launch until the end of 2019 - the period of time when PS4 reached it's peak. Just remember how great 2017 and 2018 has been for this console. And the more important fact - we have the data from Famitsu, the last I found, that PS4 Pro sold 1.5m+ in Japan alone. If it can sell that much in it's weakest market by far, it can sell way more in NA and especially Europe. Attaching the reference for Famitsu data from the article that I found via Google just in case to back up my words https://www.playstationlifestyle.net/2021/01/07/ps4-outsells-ps5-in-japan/

Yeah, and it better be on a TV that is so thin you literally can't see it from the side. Also, I expect wifi 10, at least 4 petabytes of hard drive, foldable controllers, house-wide motion tracking, and fully integrated metaverse. If they don't have that stuff, they are a joke.

I expect this generation to be slightly longer than the last, a potential PS6 launch in 2028/2029, because of COVID hitting development + the semiconductor shortage.